This invention relates to a cooling and lubricating composition and more specifically, to a water-dispersible cooling and lubricating composition particularly effective for use as a metal working fluid or as a metal removal fluid.
Metal working fluids or metal removal fluids, hereinafter referred jointly as "metal working fluids," are used for lubrication of metal cutting and forming tools. They also provide cooling for the tooling, the removal of cut chips or fragments away from the tool/work piece interface, and to provide an acceptable post-machining finished surface. Metal working fluids also have an effect of reducing the cutting forces exerted on a tool and a work piece thereby extending the life of the cutting tool significantly.
Metal working fluids are classified according to their composition and are classified as being either a Soluble Oil, a Semisynthetic Fluid, or a Synthetic Fluid. Soluble Oil metal working fluids contain no appreciable amounts of water and are provided to the end user as an oil containing speciality additives. The oil content of a Soluble Oil metal working fluid ranges from about 50-70 percent by weight of oil and typically comprise one or more mineral oils, chlorinated or sulfurized mineral oils, fatty oils, or mixtures thereof Soluble Oil metal working fluids are typically diluted with water at the user's site, from about 1-20 percent with about 5-7 percent (15:1) being the most common dilution level. Soluble oils based on mineral oil have been criticized because of their cost, flammability, their tendency to smoke, and the concern for toxicity of the aromatic compounds associated with mineral oils which may cause air quality problems in and around the cutting tools.
A Semisynthetic Fluid for metal working differs from Soluble Oil metal working fluid in that the semisynthetic neat product concentrate contains a significant amount of water, typically up to about 50-60 percent. The oil content of such metal working fluids typically ranges from about 10-40 percent and typically comprises mineral oil, an emulsifier, and other additives which, when added to water and stirred, form an oil-in-water emulsion. Such Semisynthetic Fluids used for metal working are relatively expensive and often cause air quality problems in and around the metal working tools.
A Synthetic Fluid for metal working contains a majority of water in the neat fluid and contains no mineral or vegetable oil. Functionality (lubricity, corrosion inhibition, extreme pressure functions, and the like) is provided by speciality additives. Water content of Synthetic Fluids typically comprises about 60-80 percent by weight of the metal working fluid. Synthetic Fluids, however, are relatively expensive compared to other conventional metal working fluids.
The additives in conventional metal working fluids used for metal removal often contain large amounts of sulfur. These can be in the form of sulfurized oils, sulfonates, or sulfates. The presence of significant amounts of sulfur in a metal working fluid provides nutritional sustenance for anaerobic sulfate-reducing bacteria, resulting in formation of hydrogen sulfide in the operating system. Hydrogen sulfide is extremely corrosive in very small quantities and produces an objectionable odor. Higher concentrations of hydrogen sulfide can also cause health problems.
Vegetable oils are known for having excellent lubricating properties as well as being environmentally and human considerate. For this reason they have been used in metal working fluids as lubricant additives and their reaction products have been used for lubricating purposes. Refined vegetable oils have also been used in metal working by adding water-dispersible phosphatides. However, Soluble Oil metal working fluids have not been developed that comprise a majority of crude or partially-refined vegetable oils due to the difficulties in formulating a stable pre-emulsion concentrate comprising a majority of crude or partially-refined (degummed) vegetable oils; the difficulties of providing sufficient water dispersibility; the difficulties in formulating with water-soluble corrosion inhibitors; the tendency for vegetable oils to biodegrade (go rancid) during use; the tendency for partially-refined vegetable oils to produce gumming when exposed to extreme temperatures and pressures; the tendency for vegetable oils to form a sticky residue on surfaces at ambient temperatures with time; and the objectionable odors of crude vegetable oils.
Other conventional metal working fluids that have been developed for use in the metal working industry and comprise refined fatty oils. However, refined fatty oils are significantly more expensive than nonrefined oils. Unfortunately, the presence of metal chips and bacteria in the metal working fluid limits its effective useful life. Accordingly, the use of such refined oils is relatively expensive.
Consequently, a need exists for a metal working fluid which is non-toxic, stable, ecologically acceptable, relatively inexpensive, and is effective for reducing friction caused by removing material from the cut surface of the work piece and for carrying away the heat generated by the frictional contact between the cutting or forming tool and the work piece. Further, a need exists for a metal working fluid which is non-foaming, non-inflammable, and which does not corrode ferrous metals.